This invention relates to a socket valve, capable of being coupled to a plug valve, of a quick-closure coupling for lines carrying flowing media, especially hydraulic lines.
Quick closure couplings of this kind, which consist of a plug valve and a socket valve each having a closure member spring-biased to closing position, are already known. Such couplings are utilized, for example, in commercial vehicles where they serve for the optional coupling of attachment devices or the like, but they are also used in numerous other applications.
In one known coupling of this type the closure member of the socket valve, biased by a closure spring in the closure direction and held in the closed position when the coupling halves (i.e. the socket valve and the plug valve) are separated, is a conical member which is seated and guided in a sliding sleeve. The sleeve, in turn, is seated to be axially movable inside a stationarily mountable housing which establishes the pipe connection. From one end face there extends into this sliding sleeve a recess for the plug of the plug valve, and adjoining this recess there is disposed, in the interior of the sliding sleeve, a seating surface against which the corresponding seating surface of the closure member bears under the action of the closure spring, so long as the two halves of the coupling are separated. In this position of the closure member, the socket valve is closed. In the region of the end recess for the plug of the plug valve, blocking elements extend through the wall of the sliding sleeve which, when the halves of the coupling are joined together, penetrate into an annular recess of the plug portion and lock the two halves of the coupling in the coupled position against undesired separation. These blocking means are held in the described locking position by an annular blocking cam of the stationarily mountable housing which surrounds the sliding sleeve concentrically, and the sliding sleeve is displaceable relative thereto out of the blocking position which secures the blocking means in either axial direction against the action of a holding spring axially stressed between the sliding sleeve and the housing. On either side of the annular blocking cam, the housing is furnished with a radial recessed groove, into which the blocking means can escape radially after the sliding sleeve has been displaced with respect to the position in which the blocking means are locked. The two halves of the coupling can consequently be coupled or uncoupled when the annular blocking cam of the housing is displaced axially with respect to the position which prevents radial escape of the blocking means.
In this known coupling, the sliding sleeve is held in the securing position by means of the holding spring, seated in an annular space between the sliding sleeve and the housing and axially stressed between these latter, and in this securing position the blocking cam concentrically surrounds the blocking means and thereby prevents their radial escape. The arrangement is such that the annular space which seats the holding spring extends in equal parts radially into the housing and into the sliding sleeve, and the ends of the holding spring engage, in the region of the cylindrical contact surface, simultaneously against the annular shoulders, bounding the annular space of the sliding sleeve and of the housing, so that independently of the direction an axial displacement of the two components relative to each other always takes place only against the action of the prestressed holding spring. In the interest of secure holding of the sliding sleeve in the securing position, the holding spring must possess a predetermined stiffness (i.e. spring characteristic) and when a new plug valve is being coupled or uncoupled, correspondingly large axial forces have to be exerted. Moreover, it is possible, in the case of a breakage of the holding spring which cannot entirely be precluded, for accidental uncoupling to take place. Taking into account the plant unit being supplied with working medium through such a coupling, such accidential uncoupling can lead to dangerous situations.